The development of atherosclerosis is likely to involve local stimulation of smooth muscle cell proliferation by platelet-derived growth factor. PDGF is produced by endothelial cells and is regulated by several biologically active substances at the transcriptional level. During atherogenesis, this PDGF may act in a paracrine manner to activate PDGF receptors abnormally expressed on neighboring smooth muscle cells, leading to mitogenesis. Thus atherosclerosis may result form the disordered regulation of PDGF and PDGF receptor gene regulation in vascular cells. The first goal of this proposal is to provide intensive experience in basic science research to the investigator. The applicant will attend formal courses, seminars, meetings, lab discussions and journal clubs. the research experience is essential for development of the applicant into an independent investigator in the field of vascular biology. The second goal is to elucidate the molecular mechanisms involved in the control of PDGF and PDGF receptor gene expression in vascular cells. These studies will contribute significantly to understanding growth and repair processes in the vessel wall. A long term goal is the identification of new therapeutic strategies for the prevention and treatment of atherosclerosis and related vascular diseases. The specific research aims include the isolation and characterization of genomic clones of the PDGF receptor and PDGF A and B chain genes using standard techniques. Subsequently, regions of these genes will be fused to reporter genes and transfected into various cell types. By appropriate manipulation, attempts will be made to identify cis-acting elements that participate in 1) the bidirectional regulation of PDGF gene expression of the PDGF receptor gene, which may involve unusual controls related to its tandem linkage to the c- fms gene. In addition, DNA binding proteins will be characterized by mobility shift and DNAse I footprinting assays of nuclear extracts, guided by the above studies. If time permits, attempts will be made to isolate one or more cDNA clones for these proteins and standard methods. Isolation of cDNA clones will allow eventual development of reagents necessary to better understand the regulatory properties of this system.